Housings for power-driven abrasive tools

ABSTRACT

A housing adapted for rigid attachment to a portable tool having a rotary output shaft. A plurality of flexible posts are formed integral with the housing and have an abrasive backing plate attached thereto. Eccentric means on the backing plate is attachable to the output shaft and transmits motion to the backing plate.

United States Patent [451 May 30, 1972 Flack [54] HOUSINGS FOR POWER-DRIVEN ABRASIVE TOOLS [72] Inventor: John Henry Flack, Ruislip, England [73] Assignee: The Black and Decker Manufacturing Company, Towson, Md.

[22] Filed: Aug. 12, 1970 [21] Appl. No.2 63,216

[52] U.S.Cl. ..5l/170 MT [51] ....B24b23/00 [58] Field of Search ..51/170 MT, 170, 170 TL [5 6] References Cited UNITED STATES PATENTS 2,683,336 7/1954 Scace ..5 H170 MT 3,136,099 6/1964 Tully et al. ..51/170 MT 2,929,177 3/1960 Sheps ....5l/170 MT 2,893,177 7/1959 Bruck ..51/17O MT Primary Examiner-William R. Armstrong Att0rneyLeonard Bloom, Joseph P. Slotnik and Edward D. Murphy [5 7] ABSTRACT A housing adapted for rigid attachment to a portable tool having a rotary output shaft. A plurality of flexible posts are formed integral with the housing and have an abrasive backing plate attached thereto. Eccentric means on the backing plate is attachable to the output shaft and transmits motion to the backing plate.

6 Claims, 4 Drawing Figures Patented May 30, 1972 3,665,654

2 Sheets-$heet 2 awe/who e JOHN H ENRY FLACK HOUSINGS FOR POWER-DRIVEN ABRASIVE TOOLS SUMMARY OF THE INVENTION This invention relates to housings for power-driven abrasive tools.

Existing tools of this kind include a housing for receiving the drive shaft of the power unit and a backing plate, which is operatively connected to the drive shaft, for carrying the abrasive material. These tools may include a power-driven abrasive tool for use with a rotary power unit, which includes a housing for receiving the drive shaft of the power unit and a backing plate which is arranged, in use, for operative connection to the drive shaft, the backing plate and the housing being mounted on opposite ends of a number of retaining pillars, made entirely of elastromeric material, one end of each pillar being so shaped that the backing plate may be detachably fastened thereto.

According to the present invention a housing for a powerdriven abrasive tool is made of resilient material and includes a number of integral downwardly depending retaining pillars for holding the backing plate on the tool. Each pillar may be constituted by a number of downwardly depending fingers. In this case the fingers forming each pillar can merge at their free ends to form a retaining boss for holding the backing plate. If the boss is of hollow construction then the backing plate may simply be secured to the pillars by means of fastening means passing through the bosses. The fingers of each pillar may extend from the periphery of a corresponding orifice formed in the roof of the housing. The housing may be made of polypropylene although any material having a degree of resilience suitable for withstanding the forces exerted in a power-driven abrasive tool may be used.

Further, according to the present invention a power-driven abrasive tool for use with a rotary power unit includes a housing as defined above, the housing receiving the drive shaft of the power unit; and a backing plate which is arranged, in use, for operative connection to the drive shaft, the backing plate may be generally rectangular, a retaining pillar being mounted in each comer thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a part cut-away, part sectional side elevation of an orbital sander attachment;

FIG. 2 is an internal part-sectional side elevation of the housing for the attachment shown in FIG. I, the other side of the housing having an identical appearance;

FIG. 3 is a plan view of the housing shown in FIG. 2, taken from above; and

FIG. 4 is a section taken on the line AA of FIG. 2.

DETAILED DESCRIPTION The orbital sander shown in FIG. 1 consists of a housing 1 provided with four integral, downwardly depending pillars 2 on the free ends of which is mounted a rectangular backing plate 3. The plate 3 is provided at its ends with a pair of rotatable clamping rods 4 and 5 which are adapted to clamp the ends of a sheet of abrasive paper, not shown, so that it is held taut against a rectangular pad 6 secured to the underside of the plate 3 by adhesive. The pad 6 may be made of felt, sponge rubber or any synthetic material exhibiting a degree of resilience.

The housing 1 of the attachment is formed with a pair of lugs 7 which engage in corresponding slots formed in the casing of a rotary power unit, not shown, such as for example an electric drill. In order to prevent vibration between the attachment and the power unit, the housing 1 is provided with a sliding block 8 formed with engaging tabs 9 which locate in corresponding slots in the casing of the power unit. Movement of the block 8 is provided by means of a manually adjustable wing nut 10 which is provided with a threaded shank 11 passing through the housing and engaged with an internally threaded portion of the block 8.

An eccentric counter balance mounted within the housing comprises a threaded eccentric 12 for screwing into the drive spindle of the power unit, a counterweight l3 and an eccentric shaft 14 which is rotatable within a bearing 15 secured to the backing plate 3. Because the eccentric I2 and the shaft 14 are laterally off-set one to the other in operation, the backing plate 3 will execute eccentric orbital movement about the longitudinal axis of the eccentric 12. Consequently, each grain of the abrasive paper will traverse a small orbit so as to present every sharp cutting edge to the work.

Referring now to FIGS. 2 to 4 it will be seen that the housing 1 is of unitary construction and is, in fact, molded in one piece with the pillars 2 from a resilient material such as polypropylene. Each pillar is constituted by three depending fingers 2 which extend from a cylindrical orifice 16 formed in each comer of the roof of the housing and which merge at their free ends to form a hollow retaining boss 17. The latter are used for securing the backing plate to the pillars by means of bolts 18 which pass through the bosses and engage with nuts 19, see FIG. 1. It will be understood that the backing plate may be secured to the ends of the pillars in other ways. Furthermore, although the pillars described above comprise three fingers they may be constructed with four or more or even two depending on strength requirements.

It will be evident that an advantage of the housing construction described above is that while the pillars are sufiiciently flexible to allow orbital movement of the backing plate they are also very rigid in the axial direction. Consequently, eccentric forces caused by the operator applying more axial pressure to one or more posts than the remainder in an attachment having, for example, flexible rubber posts, will not now occur. The housing construction described above therefore has the advantage of preventing the abrading means from shifting its working plane and causing irregular orbiting.

Clearly another important advantage of the housing construction described above is that it is cheaper to produce than those constructions which have separate pillars and consequently additional assembly parts. It is also much more efficient in operation and, in particular, absorbs less heat energy than existing constructions and consequently allows more driving power to be used for abrading purposes.

It will be understood that the housing and pillar construction described in this specification is not limited in application to orbital sander attachments or arrangements but can be used in conjunction with any power-driven tool in which there is relative movement between the backing plate and the housing.

I claim:

1. A housing for a power-driven abrasive tool, the housing being made of resilient material and including a number of integral downwardly depending retaining pillars for holding the backing plate of the tool, each of said pillars being constituted by a number of downwardly depending fingers which merge at their free ends to form a retaining boss for holding the backing plate of the tool.

2. A housing for a power-driven abrasive tool, the housing being made of resilient material and including a number of integral downwardly depending retaining pillars for holding the backing plate of the tool, each of said pillars being constituted by a number of downwardly depending fingers extending from the periphery of a corresponding orifice formed in the roof of the housing and merging at their free ends to form a retaining boss for holding the backing plate of the tool, each said boss being of hollow construction to allow passage of fastening means therethrough for securing the backing plate of the tool to the pillars.

3. A housing for a power-driven abrasive tool, the housing being made of resilient material and including a number of integral downwardly depending retaining pillars for holding the backing plate of the tool, said housing receiving a drive shaft of a power unit of said tool, said backing plate being arranged, in use, for operative connection to said drive shaft, said backing plate being fastened to the free end of said retaining pillars.

direction and relatively stiff in the longitudinal direction thereof.

5. An assembly as designed in claim 4 wherein each said pilla: is formed by a number of downwardly depending fingers.

6. An assembly as defined in claim 5 wherein said fingers of each said pillar merge at their free ends to form a retaining boss, said bosses including means for attachment to said backing plate. 

1. A housing for a power-driven abrasive tool, the housing being made of resilient material and including a number of integral downwardly depending retaining pillars for holding the backing plate of the tool, each of said pillars being constituted by a number of downwardly depending fingers which merge at their free ends to form a retaining boss for holding the bacKing plate of the tool.
 2. A housing for a power-driven abrasive tool, the housing being made of resilient material and including a number of integral downwardly depending retaining pillars for holding the backing plate of the tool, each of said pillars being constituted by a number of downwardly depending fingers extending from the periphery of a corresponding orifice formed in the roof of the housing and merging at their free ends to form a retaining boss for holding the backing plate of the tool, each said boss being of hollow construction to allow passage of fastening means therethrough for securing the backing plate of the tool to the pillars.
 3. A housing for a power-driven abrasive tool, the housing being made of resilient material and including a number of integral downwardly depending retaining pillars for holding the backing plate of the tool, said housing receiving a drive shaft of a power unit of said tool, said backing plate being arranged, in use, for operative connection to said drive shaft, said backing plate being fastened to the free end of said retaining pillars.
 4. An abrasive tool assembly comprising a backing plate, eccentric means operatively connected to said backing plate and adapted to cause said plate to orbit, means for attaching said backing plate to tool means adapted to drive said eccentric means, said attaching means including a unitary one-piece housing constructed of resilient material and including a plurality of dependent, elongated pillars extending toward said backing plate, said pillars being adapted for connection to said backing plate, and being relatively flexible in the lateral direction and relatively stiff in the longitudinal direction thereof.
 5. An assembly as designed in claim 4 wherein each said pillar is formed by a number of downwardly depending fingers.
 6. An assembly as defined in claim 5 wherein said fingers of each said pillar merge at their free ends to form a retaining boss, said bosses including means for attachment to said backing plate. 